Effect of temperature and relative humidity on the development of Oryzaephilus surinamensis L. (coleoptera: Silvanidae) reared on dried noodles

Abstract

The saw-toothed grain beetle, Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae), is a secondary pest of stored products, previous studies have focused on grains and ignored their growth characteristics in packaged commodities. This study aimed to investigate the developmental and reproductive biology of O.surinamensis at 20–36 °C and 65%–85% relative humidity (RH) reared on dried noodles. The optimum temperature and humidity of O. surinamensis reared on dried noodles were 28 °C/85% RH, the index of population control was 0.24, the generation period was 49.86d, and the generation survival rate was 40%, the highest fecundity was 7.83 eggs. The temperature was more affected than relative humidity on the generation period, fecundity, and survival rate of O. surinamensis. The development of O. surinamensis was all completed in the range of 28–36 °C except 20 °C; the larval and pupal stages were more affected than the egg stage at 65%∼85% RH. Under the experimental conditions of temperature and humidity, the intrinsic rate of increase, and doubling time of the population were negative, and the population trend index was less than 1; the reproductive parameters of O. surinamensis decreased slightly as temperature (28–36 °C) increased or humidity decreased. Simulating different temperature and humidity conditions in dried noodles packaging, the O. surinamensis did not complete the generation development. The survival rate of O. surinamensis of each developmental stage and fecundity was highest at 28 °C/60% RH, followed by 36 °C/60% RH. The results showed that the ambient temperature below 20 °C and RH below 65% were beneficial to the prevention of O. surinamensis and its prevention in dried noodles is focused on the invasion of adults and eggs.